<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    * {
        margin: 0;
        padding: 0;
    }

    li {
        list-style: none;
    }

    /* 
      响应式的布局尺寸,这个是根据领导的需求来定义的 
     */

    /* - 超小屏幕（手机小于 768px ）设置宽度 100%  */
    @media screen and (max-width: 768px) {
        .container {
            width: 100%;
            background-color: skyblue;
        }

        .container ul {
            flex-wrap: wrap;
        }

        .container ul li {
            width: 33.33%;
            height: 30px;
            line-height: 30px;
        }
    }

    /* - 小屏幕（平板，大于768px）设置宽度 750px（为什么宽度会小一些是因为两边要留白 ） */
    @media screen and (min-width: 768px) {
        .container {
            width: 750px;
            background-color: blue;
        }
        .container ul {
            justify-content: space-around;
            align-items: center;
        }

        .container ul li {
            width: 100px;
            height: 30px;
            line-height: 30px;
        }
    }

    /* - 中等屏幕（桌面显示器，大于等于992px）宽度设置970px */
    @media screen and (min-width: 992px) {
        .container {
            width: 970px;
            background-color: pink;
        }
        .container ul {
            justify-content: space-around;
            align-items: center;
        }

        .container ul li {
            width: 100px;
            height: 30px;
            line-height: 30px;
        }
    }

    /*  - 大屏幕（大桌面显示器，大于等于1200px） 宽度设置 1170px  */
    @media screen and (min-width: 1200px) {
        .container {
            width: 1170px;
            background-color: red;
        }

        .container ul {
            justify-content: space-around;
            align-items: center;
        }

        .container ul li {
            width: 100px;
            height: 30px;
            line-height: 30px;
        }
    }

    .container {
        height: auto;
        margin: auto;
    }

    .container ul {
        display: flex;
    }
</style>

<body>
    <div class="container">
        <ul>
            <li>导航栏</li>
            <li>导航栏</li>
            <li>导航栏</li>
            <li>导航栏</li>
            <li>导航栏</li>
            <li>导航栏</li>
        </ul>
    </div>
</body>

</html>